Piston ring



Sept. l, 1936. MILLER 2,052,642

INV ENTOR RaQOhMllez'. M cmu. *TU S ATTORNEY. v

Patented Sept. l, 1936 PATEN'II OFFICE PISTON RING Ralph Miller, Easton, Pa., assigner to Ingersoll- Rand Company, Jersey City, N. J., a corporation of New Jersey Application segun is. 1935, serial No. 36,250 '3 claims. (ci. sos-'31) This invention relates to packing devices, and. .more particularly to a piston ring of the resilient metallic type. v

The present invention is particularly adapted for use on pistons of high speed engines in which the rate of pressure rise is extremely rapid, so that, unless suitable provisions arefmade to assure reasonably free movement of the piston ring in its groove, the prevailing `pressure acting on one side of the ring presses the other side of the ring against the adjacent wallof the ring groove with such force as to prevent movement of the ring in the groove. Thus, in engines in which the piston or the cylinder, or both, are worn to l5 a, considerable degree, so that during its movement the piston is capable of tilting relatively to the cylinder, one side of the piston ring may lie entirely in the ring groove. lIftheu the preveiling pressure maintains the ring in that posiu tion a portion of the outer surface o the ring may remain out of contact with the cylinder wali and blow-by will take place, This condi tion not only results in a loss ofpower but operates to remove the oil :dim on the cylinder waii further weer on these parts.

it is accordingly contemplated to minimise rictional .contact between the piston and the piston ring so that the entire periphery of the piston ring may `cmistantly remain in Contact .with the Wall of the cylinder wherein the piston operates.

. Itis a further cbject'to subject certain surfaces vor portions of such surfaces oi the piston ring vutilize only as much area of effective contact between the piston ring and the piston as is necessary to prevent leakage through the ring groove. ther objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specication and forming a part thereof,

Figure 1 is an elevation, partly broken away, of a portion of an engine cylinder and a piston, 'the latter being equipped with a piston ring constructed in Aaccordance with the practice of the invention, A

Figure 2 is a transverse view through Figure l on the line 22, and

Figure 3 is an'enlarged View of a section of the piston ring. Referring 'more particularly to the drawing, 2d designates a cylinder, as for instance that of an internal combustion engine, and 2l a piston (i5 reciprocable therein. A head 22 seated on the and the piston and is, therefore, the cause oi simuitaneously to pressure of th'e same value and end oi the cylinder 2li, and which may be secured thereto in any suitable manner, cooperates with the piston 2l and the cylinder to ldefine a combustion 'chamber 23.

lThe piston 2l is provided adjacent itsend with an annular groove or grooves 24 for the reception of piston rings 25 whichcooperate, in the usual manner, with the wall of the cylinder 20 to prevent leakage of pressure from Vthe com# bustion chamber 23. V

- The piston ring 25, constructed in accordance with the practice of the invention. consists of a resilient metallic member which is split transversely, as at' 28, to permit of free contractile and expansible movement o the ring.

As is Well known, portions of rings of the type to which the present invention pertains are subjected directly to the pressure prevailing in the combustion chamber. In structures in which the ring has a close sliding A:dt in the groove such pressure as may find entrance into the ring is wire-drawn and, hence such a weak force that, in coniuncton with the inherent resiliency ci the piston ring, it is una-ble to overcome the pressure gradient acting on the outer surface or the ring. In consequence oi this condition the ring remains contracted. and pressure lea-irs from the combustion chamber along the Wall of the cylinder. in order avoid this objectionable occurrence the piston ring ci which the entire periphery constitutes a sealing surface is con structed oi less width than the groove Zl to provide a clearance 2l shove the ring The clearance 2l will thus he in direct communication with the combustion chamber through the clearance existing between the periphery of the piston 2l and the Wall oi the cylinder 2B, and designated "alti, and the. entire upper surface of the piston ring iii will constitute a pressure area 3i against which prevailing pressure constantly acts to press the opposite. side of the piston ring against the lower surface 32 of the groove.

The groove 263, as is customary, is of greater .depth tha'nthe distance between the periphery and the inner surface of the ring so that in the event of relative lateral movement between the piston and the ring the interior surface of the ring will not abut the adjacent surface 33 of the groove. A space 315 willn thereby exist between the inner surface of the ring 25 and the surface.

33 and, in order to permit the free transmission of prevailing pressure into said space, the upper side or surface constituting the pressure area 3l is provided with e. sexies of channels 35 which extend from the periphery to the inner surface 10 tween the ring and the piston without, however,

a is

actingagainst the pressure area sinon-effective .d

andthereby reduce frictional engagement between `tliewring andthe surface 32 to-a value which willbe suilicient to maintain a seal bebeing of such degree-as to cause undue wear'on the cooperating surfaces, the piston ring is proi vided at its lower side with an Aannular groove I! intermediate the periphery and the inner surface of the ring. The groove 3l isconnecteci with a zone of prevailing pressure. as for instance vthe channels 35, by pasages l'l in the A The portion of the lower of the piston ring including the groove vand the area between v the groove and the innersliri'aceof the ringlthus servesas a pressure area Il which willxbe subyj'ected to pressure lof thesame value as thatexisting in the groo the difference between the pressin'egradient acting against a portion vltonthe lower side'of the ring', and lying exterioriy-of the grooveyl.- and the prevailing pressure acting against a corre- SDOnding portion on the upper side of the ring.

In practice, the present invention has been found to be highly eillcient for effecting a seal between the piston-and the cylinder. 'By providing free communication between prevailing pressure and the inner surface' of the ring preveiling pressure may be transmitted into the ring freely' and thus may constantly augment .the resiliency of the ring to overcome the pressure.

. gradient onrthe periphery of the ring. The *ring will', therefore, remain in constant contact with 38 and the 'space It. The cor- 'responding po ion on theopposite'side of the J ring will,- therefore, be balanced; Thev pressure serving to maintain the rringinsealing messe nrent with the :surfacexll of the groove will be crassa the wall of the cylinder and prevent loss of pressure at that'point. A further highly desirable advantage of the present invention is, that byl partly balancing the pressure acting against the side of the ring adjacent the source of pressure only as much of the prevailing pressure acting against the surface 3| as is required to maintain an adequate seal between the ring and the surface 32 of thev groove will be eiective for this purpose. .The piston and the ring may, thereufore, move freely laterally with respect to each other and with a minimum degree of friction so that the cooperating surfaces relied upon to maintain a seal between the piston and the ring will b e subjected to only a minimum of wear.

1. Af piston ring of which one entire side constitutes a' pressure area adapted to beexposed to lprevailing' pressure when. in use and having channels insuch. side to` convey prevailing pres-l the `interior of the ring', there being an annular groove in the opposite'side of the ring intermediate the periphery. and the inner v 'i oi' the ring; said ring having passages intermediate itsv in nerjand outer lsurfaces to afford communication between the channels and the groove.-

- 2.'A.piston havinga series of channels v extendingfentirely acrossjon'e side surface and beingipassages in the ring to ail'ord communicaannular groove intheother side surface, there tionbetween each'ch'annel and the groove, aniiaf peripheral sealing surface extending. 'from 'one side to the other vof the ring. l Y 3. A piston ring havinga channel extending entirelyacross oneside surface anda groove in.

theoth'er sidesurface intermediate the inner and cuterisurraeeslof the nag. said ring having a passage afford communication, between the v channel and the grove, and a peripheral sealing surface extending from one-side to the other of v therin. v l

HARALPHMIILER: 

